The identities of both are unknown. Police are yet to comment on the actions of the bystanders and if they assisted or placed themselves in harm's way.

Premier Daniel Andrews praised police and those that intervened.

"Those strangers, people who were bystanders who knew nobody involved, who stepped in without a moment's hesitation, to render support and assistance to the brave members of the Victoria Police, they too, people whose qualities make all of us proud as well," Mr Andrews said.

Thank you to the @VictoriaPolice officers who responded so bravely, and the every day Victorians who came to the aid of complete strangers. Please continue to avoid the area. Anyone with information should attend Melbourne West Police Station to make a statement.